Thyroid carcinoma presenting as an autonomous thyroid nodule

Follicular variant of papillary thyroid carcinoma presenting as a toxic nodule by I-123 scintigraphy

The risk of malignancy in a "hot" thyroid nodule detected by radioiodine scintigraphy is rare. We report a case of a 63-year-old man with a hyperfunctioning nodule demonstrated by radioiodine scintigraphy and cytology suspicious for follicular variant of papillary thyroid carcinoma (FVPTC). There were no locoregional or distant metastases at initial diagnosis. Histopathologic examination following thyroidectomy confirmed the presence of an encapsulated FVPTC. A year into follow-up, his I-131 whole body scan performed following the withdrawal from exogenous thyroid hormone was negative, whereas his serum thyroglobulin (Tg) levels were intermediate. A subsequent PET/CT scan revealed a small, but stable, metabolically active pretracheal lymph node, which on biopsy was confirmed to be stage III FVPTC. In conclusion, the presence of hyperfunctioning thyroid nodule(s) does not preclude malignancy and, therefore, proper cytohistologic evaluation in such patients may help to exclude a coexistent thyroid carcinoma. Patients treated for localized PTC may benefit from serial PET/CT follow-up in the early detection and management of recurrence or distant metastases.

Is it useful to routinely biopsy hot nodules in iodine deficient areas?

Incidence of nodular thyroid disease as well as that of functioning thyroid nodules (FTN) increases dramatically in iodine deficient (ID) areas. Cancer is extremely rare in FTN; thus, some do not routinely biopsy and treat them with radioactive iodine (RAI) straight away or follow-up. The outcome of 296 patients followed or treated at our institution for solitary or multiple FTN were retrospectively evaluated. Hospital records of 224 female, 72 male patients, with a mean +/- SD age of 54.9 +/- 12.4 yr and followed for 22 (0-156) months were examined. 175 patients had solitary, 121 had multiple hot or warm nodules. 230 (77.7%) of the patients received RAI treatment. 402 fine needle aspiration biopsies (FNABs) were performed on 260 patients and on 343 FTN (381 benign and 21 suspicious diagnoses). Eleven of the patients were operated for suspicious FNAB results and 10 were followed-up. Only one nodule turned out to be malignant. Malignancy is extremely rare in functioning thyroid nodules (0.34%) and some of malignant cases could be predicted by their suspicious clinical features. Routine practice of treating FTN with RAI therapy is reasonable in clinically low-risk patients. FNAB is reserved for cases with suspicious clinical features, resulting in fewer surgeries and reduced cost.

Diagnosis and management of the autonomously functioning thyroid nodule: the Walter Reed Army Medical Center experience, 1975-1996

In order to characterize the clinical and laboratory features of autonomously functioning thyroid nodules (AFTNs), and to assess optimal diagnosis and management of patients with this disorder, we performed a retrospective analysis of 49 such patients over a 22-year period encompassing January 1975 to November 1996. The following data were analyzed: thyroid hormone levels, thyroid scintiscan, radioiodine uptake, fine-needle aspiration biopsy, triiodothyronine (T3) suppression testing, thyrotropin-releasing hormone (TRH) stimulation test, and thyroid ultrasound. Clinical outcomes assessed included persistent hyperthyroidism, hypothyroidism, and nodule shrinkage after treatment, or in patients followed without definitive therapy, nodule growth, spontaneous degeneration, and progression to hyperthyroidism. Biochemical hyperthyroidism, often subclinical, was found in 73.5% of patients at presentation and in an additional 24.4% of patients during subsequent follow-up. The introduction of sensitive thyrotropin (TSH) testing during the period of study resulted in a decrease in the use of the T3-suppression test and TRH stimulation test from 100% and 20%, respectively, in the period from 1976-1980, to 4% each in the period from 1991-1996. T3-thyrotoxicosis occurred in 12.2% of patients. Thyrotoxicosis at any time during the course of follow-up was positively correlated with nodule size at diagnosis. Definitive therapy, used in 42.8% of patients, consisted of radioiodine ablation (38.1%) or thyroidectomy (61.9%). No patient had recurrence of thyrotoxicosis after definitive therapy, but 25% became hypothyroid. During follow-up for a mean of 30.9 months, nodules enlarged in 25% of patients overall, or 33% of patients not receiving definitive therapy. Cystic degeneration was documented in 26.5% of patients, although this change rarely reversed subclinical hyperthyroidism. The diagnosis of an AFTN requires a demonstration of TSH-independent nodular hyperfunction. The introduction of sensitive TSH assays has simplified the evaluation of AFTN patients and revealed a high prevalence of subclinical thyroid hyperfunction in this disorder. In view of current increased awareness of adverse consequences associated with subclinical hyperthyroidism and the rarity of spontaneous resolution of hyperthyroidism in AFTN patients (despite a propensity for spontaneous hemorrhage), definitive therapy is recommended. Both radioiodine and hemithyroidectomy have high cure rates and a low posttreatment incidence of hypothyroidism.

Controversies in the management of cold, hot, and occult thyroid nodules

Some aspects of thyroid nodule evaluation and management remain controversial. Radionuclide scanning provides functional information about nodules and differentiates cold from hot nodules. Although thyroid cancers are cold on scan, most cold nodules are benign. Ultrasonography visualizes the thyroid gland and nodules with remarkable clarity and provides structural information about location, number, size, and consistency of nodules. Widespread application of ultrasonography has resulted in the frequent discovery of incidental (occult) nodules in the general population. The clinical significance of these nodules remains unknown, and their management has created a dilemma for physicians. Current cost-effective evaluation of nodules does not include scanning or ultrasonography as routine frontline tests. In most centers, fine-needle aspiration biopsy has supplanted imaging studies as the routine initial procedure for differentiating benign from malignant nodules. Cytologic diagnosis is reliable and inexpensive, and it results in a better selection of patients for surgery. Limitations include false-negative diagnoses, nondiagnostic results, and indeterminate "suspicious" results. Laboratory test results are usually normal, but determination of serum thyrotropin may identify a hot nodule, and plasma calcitonin may help diagnose medullary thyroid carcinoma. Treatment of thyroid nodules is controversial. In some practices, benign colloid nodules are treated with suppressive doses of levothyroxine. Recent reports cast doubt on the efficacy of this approach, and it is no longer acceptable to select patients for surgical treatment on the basis of suppressive therapy. Furthermore, suppressive levothyroxine therapy may be associated with significant bone and cardiac side effects, especially in elderly patients and postmenopausal women. Our approach is observation for most patients, and we suggest a careful risk-benefit analysis when suppression is considered. Hot (autonomous) nodules can be treated with radioiodine, surgery, or ethanol injection. The use of sensitive thyrotropin assays has revealed that the "euthyroid" hot nodule is often associated with subclinical hyperthyroidism, warranting treatment if risks of osteoporosis are significant. Small (< 1.5 cm) occult nodules can be observed. Larger (> 1.5 cm) nodules can be selectively evaluated by ultrasonographically guided fine-needle aspiration. It is prudent to consider cost of care, risk-benefit analysis, and the low incidence of malignancy in thyroid nodules when diagnostic tests are selected and the treatment plan is outlined.